Correct arm64 SignExtension (#110635)

mikelle-rogers · web-flow · commit 43b89b4a40f7 · 2024-12-12T15:23:12.000-08:00
* correct arm64 SignExtension

* check for the 28th bit
diff --git a/src/coreclr/debug/ee/arm64/walker.cpp b/src/coreclr/debug/ee/arm64/walker.cpp
@@ -278,9 +278,9 @@ BOOL  NativeWalker::DecodePCRelativeBranchInst(PT_CONTEXT context, const PRD_TYP
     {
         offset = (opcode & 0x03FFFFFF) << 2;
         // Sign extension
-        if ((offset & 0x4000000)) //Check for 26'st bit
+        if ((offset & 0x8000000)) //Check for (26 + 2)'st bit
         {
-            offset = offset | 0xFFFFFFFFF8000000;
+            offset = offset | 0xFFFFFFFFF0000000;
         }
 
         if ((opcode & 0x80000000) != 0) //BL

Original file line number	Diff line number	Diff line change
`@@ -278,9 +278,9 @@ BOOL NativeWalker::DecodePCRelativeBranchInst(PT_CONTEXT context, const PRD_TYP`
`278`	`278`	`{`
`279`	`279`	`offset = (opcode & 0x03FFFFFF) << 2;`
`280`	`280`	`// Sign extension`
`281`		`- if ((offset & 0x4000000)) //Check for 26'st bit`
	`281`	`+ if ((offset & 0x8000000)) //Check for (26 + 2)'st bit`
`282`	`282`	`{`
`283`		`- offset = offset \| 0xFFFFFFFFF8000000;`
	`283`	`+ offset = offset \| 0xFFFFFFFFF0000000;`
`284`	`284`	`}`
`285`	`285`
`286`	`286`	`if ((opcode & 0x80000000) != 0) //BL`